In this article we are going to talk about How to Grow Perennials From Seeds. The advantages of growing perennials from seeds (rather than store-bought seedlings) are that seeds cost less and come in a wider variety of species. But there are downsides.
First, it can take more than a year for a perennial grown from seeds to bloom for the first time, so it can be a major time investment. Second, though you can sow most annuals outside if you’d like, most perennials do much better if they’re grown to seedling size inside.
Growing seedlings inside lets you control temperature and light conditions closely, but it also requires an investment in equipment and space inside your home.
Supplies for Sowing Perennial Seeds Indoors
To sow seeds indoors, you’ll need some tools and supplies:
- Containers: Any 3″-deep receptacle that can hold potting soil and allow for drainage can serve as a container for your seeds. You can make your own containers by punching small drainage holes in the bottoms of egg cartons, halved milk or juice cartons, or plastic food cartons, such as those used for cottage cheese or yogurt. You can also get plastic seedling containers at garden centers or online gardening stores. Before using any type of container for seedlings, it’s a good idea to sterilize it by washing it in the dishwasher or wiping it out with a mixture of 1 part household chlorine bleach to 10 parts water.
- Trays: Rather than handle each container individually, place the containers on trays. The best trays have holes in the bottom that allow for drainage and also allow you to water the seedlings from the bottom when it becomes necessary to do so.
- Fluorescent grow lamps: If you have a space in your home that can provide your seeds and seedlings with enough natural light each day, then you won’t need fluorescent lamps to give your plants extra light. But few people have ideal natural light conditions inside their homes. To sow seeds indoors, you’ll likely need to buy fluorescent grow lamps, which are sold at garden centers and online gardening retailers. You can buy just the lights and rig them yourself over your seed trays, or you can get a light stand that holds the lights over the trays.
- Potting soil: It’s best to grow your seeds in commercial potting soil rather than soil from your garden, since garden soil can contain insect pests and germs. Look for specially formulated germinating mix, which is designed to provide the best environment for sprouting seeds and seedlings. If you want to use soil from your garden, you can sterilize it by spreading it in a shallow baking pan and then heating the soil in the oven to 180°F and keeping it at that temperature for at least 30 minutes.
- Spray bottle: A spray bottle is the best way to water seeds and seedlings. Make sure to use a spray bottle that’s dedicated exclusively to gardening and hasn’t ever been used to spray chemicals—chemical residues can harm your plants.
- Fertilizer: Once the seeds have sprouted, you can aid their growth by applying a soluble powdered or liquid fertilizer. Look for a balanced, complete fertilizer. If you’d like to use an organic fertilizer, fish emulsion is a good choice. If possible, look for a fertilizer specially formulated for germinating plants. ( )
- Plastic wrap: Use this to cover the containers after the seeds have been sown, to keep in moisture.
How to Sow Perennial Seeds Indoors
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For most perennials, you should sow the seeds indoors about three months before the start of summer (when you can transplant them outside), though more or less time may be required depending on the species. The seed packet will provide specifics.
- Find a good spot: Most perennials need a stable air and soil temperature of about 70°F to sprout and grow. Make sure to locate your indoor sowing setup in an area of your home where you can control the temperature. If you want to grow seeds that require a soil temperature well above 70°F for germination, you may have to get a heating mat, an electric mat that you place under containers to warm the soil within them.
- Moisten the soil: Moisten the potting soil using the spray bottle. The soil should be damp and, if molded into a ball, should hold together—but it should not be dripping wet.
- Put the soil in the containers: Fill the containers with the soil to a height of about 1″ from the top. Keep some extra potting soil in reserve.
- Sow the seeds: Sow the seeds in rows across the potting soil. You can sow roughly 3–4 seeds in each small container and more in each larger container. Only sow a single type of seed within a container, and label that container so you know which type of seeds it contains. It’s important that you keep different types of seeds separate and label the containers so that you transplant the different seedlings at the right times.
- Cover the seeds: Depending on the instructions on the seed packet, cover the seeds with a 1/2″ or 1/4″ layer of soil. Some seeds require light to germinate and shouldn’t be covered at all.
- Cover the containers with plastic wrap: Put plastic wrap over the containers—this keeps in moisture and promotes sprouting. Do not keep the containers under fluorescent grow lamps at this point, unless the seed packet indicates that the seeds need light to germinate.
- Check soil moistness: Every few days, remove the plastic wrap to check the soil’s moisture level. If the soil is dry, spray with the spray bottle until moist, then cover the container with the plastic wrap again.
- Give the sprouts light: When you see sprouts pushing up from the soil, remove the plastic wrap. Place the container directly under the lamps, and lower the lamps so that they’re just a few inches above the seedlings. Raise the lamps as the seedlings grow, and leave the lamps on for 12–16 hours a day.
- Water the seedlings: Once the plastic wrap is removed, the soil will lose moisture more quickly. Check the soil daily and keep it moist but not quite damp. Rather than water the seedlings using the spray bottle, at this point it’s best to water from the bottom up by dipping the tray into a sink that you’ve filled with 1–2″ of cool water. Keep the tray in the water until the moisture reaches the top of the soil.
- Thin the seedlings: Once the seedlings are 2″ high, thin them out by pulling some of the seedlings from the soil so that the others have more room to grow.
- Transplant the seedlings: Once the seedlings have grown four leaves, transplant them to larger, individual containers. First, fill the new containers with potting mix and make a hole in the soil the size of a pencil stub. Next, dump the soil gently from one of the original containers and separate the seedlings by pulling lightly on the leaves (don’t handle the roots). Place one seedling in each pencil-sized hole at the same depth it was at in the first container. Afterward, press the soil in around it.
- Fertilize the seedlings: Fertilize the seedlings after about two weeks by dissolving the fertilizer in water and fertilizing when you water. Use the fertilizer at half the strength that the packaging recommends.
Transplant the seedlings outside based on the instructions on the seed packet and on the average last day of frost in your area.